[039/119] tty_port: If we are opened non blocking we still need to raise the carrier

Greg KH
2009-12-07T00:13:04Z

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2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------
From: Alan Cox <alan@linux.intel.com>

commit 4175f3e31cc7157669aa66d46dc79de6ae0126ce upstream.

Original discussion:
http://thread.gmane.org/gmane.linux.usb.general/23217/focus=23248
or
http://marc.info/?l=linux-usb&m=125553790714133&w=2

The tty_port code inherited a bug common to various drivers it was based
upon. If the tty is opened O_NONBLOCK we do not wait for the carrier to be
raised but we must still raise our modem lines if appropriate.

(There is a second question here about whether we should do so if CLOCAL is
set but that can wait)

Signed-off-by: Alan Cox <alan@linux.intel.com>
Reported-by: Karl Hiramoto <karl@hiramoto.org>
Tested-by: Karl Hiramoto <karl@hiramoto.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/char/tty_port.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -219,6 +219,9 @@ int tty_port_block_til_ready(struct tty_
the port has just hung up or is in another error state */
if ((filp->f_flags & O_NONBLOCK) ||
(tty->flags & (1 << TTY_IO_ERROR))) {
+ /* Indicate we are open */
+ if (tty->termios->c_cflag & CBAUD)
+ tty_port_raise_dtr_rts(port);
port->flags |= ASYNC_NORMAL_ACTIVE;
return 0;
}